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. Author manuscript; available in PMC: 2008 Mar 10.
Published in final edited form as: Behav Pharmacol. 2006 May;17(3):213–222. doi: 10.1097/00008877-200605000-00002

Table 1.

Summary of Experimental Design for Experiment 1.

Experimental Condition (All injections in Home Cage except those labeled CS or NO CSa)
Nal-Naive Unpaired Paired-No CS Paired-CS
Conditioning Sessions (Days 1–4)
 T = 0 MOR VEH + CSa MOR MOR
 T = 4 hr VEH + CSa MOR NAL + NO CSa NAL + CSa
 T = 8 hr VEH NAL VEH VEH
Test Session (Day 5)
 T = 0 MOR MOR MOR MOR
 T = 4 hr VEH + CSa VEH + CSa VEH + NO CSa VEH + CSa

Abbreviations: MOR = morphine, NAL = naloxone, VEH = vehicle, CS = tone/light conditioned stimulus present in CS Session, NO CS = tone/light CS omitted during CS Session.

a

On Conditioning Days and Test Days, a 10-min operant session (Pre-CS Session) preceded the CS session, with the corresponding VEH or NAL injections administered 10 min after the conclusion of the Pre-CS Session and 5 min prior to onset of the CS Session. Note that on Conditioning Days the Unpaired group received VEH prior to the CS session, and morphine and naloxone treatment followed rather than preceded the CS session.